NAA Won't Start

phil(va) · May 15, 2019

Post a couple weeks ago. Still have problem. Tractor has been running all spring. Went to start and no go. Cranks good. Six volts. Checked spark and got blue spark that jumps 1/4 in. or more. No fuel on plugs. Good flow at carb. Removed carb numerous times. Cleaned thoroughly. Put in kit. Finally took carb to another NAA and swapped and the other one started right up with carb off one that won't start, which seems to say carb is not the problem. Gov. rod is hooked and moves freely. Tested compression, got 100-110 on all cylinders. Looked at static timing and it appears ok or at least close. Hasn't been changed anyhow. In fact nothing was changed since it started a week prior. Plug wires are correct. I'm looking at manifold, but can't see any cracks or anything wrong. No blockage at tail pipe. At wits end. Thinking there has to be a blockage in the manifold somewhere, but how would that happen just sitting? What else should I check? As ya'll know removing manifold not easy with the old rusted nuts, etc.

phil(va) · May 15, 2019

Also, suction at carb is good.

Jim L WA · May 15, 2019

Is the choke working? Have you tried starting fluid? It sounds like it must be an ignition problem of some kind. What is the actual battery voltage?

phil(va) · May 15, 2019

Choke is working. Tried starting fluid early in the process. Battery getting a little down probably , but voltage has been around 6.4 at rest (of course at rest, it won't start, duh). I'm going to put a set of points in it although it does not seem to need it. It's in a large old chicken house, semi dark, no electricity, a challenge working, 100 steep yards from shop.

phil(va) · May 15, 2019

I got it!!!!!!! Another example of carburetor problem in the ignition. Pulled cap to put in points and found crack inside cap. Put in points anyway, fired right up. So it was showing spark, about 1/4 inch of spark when grounding plug, and good steady spark on spark tester dongle which I also tried, but apparently it was not enough. I'm still a little mystified, but happy to get my mowing tractor back. Thanks to those who responded here and earlier post also.

Jim L WA · May 15, 2019

Great news Phil. You know, there is good advice on here telling us not just go and throw a bunch of parts at a problem. But there is nothing wrong with doing a full tune-up now and then. New plugs, points, condenser, rotor, and cap. Even plug wires if they are old. Evidently, there is a big difference between a spark jumping a 1/4 inch gap in the open and jumping .025 under compression. Electrons want to find the easiest path to ground and it must be easier to jump across a crack or carbon track in the distributor cap than jump that spark plug under compression.

NAA Won't Start

phil(va)

Well-known Member

phil(va)

Well-known Member

Jim L WA

Well-known Member

phil(va)

Well-known Member

phil(va)

Well-known Member

Jim L WA

Well-known Member

Similar threads